Digital image projectors are devices that project digital images onto a projection surface for presentation to an audience. The digital images are generated at a personal computer or other image source devices connected to a projector, such as DVD players, DVRs, VCRs, satellite receivers, cable systems, and video game players, among others. The projection surface may be a display screen, wall, or other surface in which projected images become visible to the audience.
There are several digital image projectors available today, including Liquid Crystal Display (“LCD”) projectors, Digital Light Processing (“DLP”) projectors, and Liquid Crystal on Silicon (“LCoS”) projectors, among others. These digital image projectors are typically used to project images onto large display screens for viewing by large audiences, such as during presentations at meetings, lectures, conferences, home theater screenings, and other venues requiring large display areas.
A desirable feature during these presentations is to have a presenter or member of the audience draw attention to particular locations or items of interest on the projection surface, such as, for example, by using a laser pointer. Laser pointers are handheld, pen-shaped devices that project a laser beam onto a surface area to generate a laser spot on the surface that is visible to the audience. Their use has become commonplace at venues where presentation materials are shown on a display screen. Most common laser pointers emit red, green, or blue light of at most 1 or 5 mWatts to avoid damage to human eyes.
Laser pointers may also include command switches or buttons for enabling remote control of basic computer functions during the presentations. For example, U.S. Patent Publication Nos. 200710030460, 2006/0227107, and 2006/0197756 and U.S. Pat. No. 6,417,840 all describe laser pointers with command switches mounted thereon to enable remote initiation of various commands at the presentation computer. The commands may include, for example, page-up and page-down commands to indicate to the presentation computer that a new image or page of presentation material is to be displayed and projected onto the projection area. In some cases, the laser spot generated by the laser pointer may function as a control cursor. The presenter may direct the control cursor to a position in the screen and emulate position-dependent commands via the switches.
These position-dependent commands require that the laser spot be detected and its position determined on the projection surface. Various approaches have been used to locate laser spots on projection surfaces, including integrating image sensors with the projection surface or with the projection device. The position of the laser spot may be detected by the image sensors and determined by a controller or computer connected to the image sensors.
In United States Patent Publication Number 2004/0012565, for example, the projection surface is an interactive tiled Organic Light Emitting Diode (“OLED”) display with an array of photosensors integrated into it for detecting the laser spot in a given tile of the display. A display controller is connected to the display screen to generate a signal representing the location of the laser spot. The location is transmitted from the controller to the presentation computer, which is programmed to respond to the signal to selectively change the image being displayed.
Image sensors integrated into projection devices are provided, for example, in U.S. Pat. No. 6,050,690 and U.S. Patent Publication Nos. 2007/0030460 and 2006/0170874. The image sensors may be used to detect a laser spot generated by a laser pointer on a projection surface. The position of the laser spot may be used together with pulsing signals generated at command switches on the laser pointers to emulate mouse click operations or other commands at the projection device or presentation computer. In one example, a user may press a button mounted on the laser pointer to cause it to pulse at a given frequency. The pulsation indicates to the projection device that the laser pointer position is to be monitored for a mouse “dragging” event until the user presses the button again to stop the pulsation. Different frequencies may be used to activate different mouse events.
These and other currently-available projection devices either require a custom-based projection surface (such as the tiled OLED display screen described above) or a laser pointer with command switches to provide position-dependent commands to a presentation device. Using command switches on laser pointers to emulate mouse commands may, at best, be cumbersome to the user operating the laser pointer. The user must change focus from giving the presentation to operating the switches. The switches may be prone to error or fail entirely during a presentation.
Furthermore, the projection devices and laser pointers available today may only be used to assist in the remote control of presentation computers. They are not able to assist in the remote control of other devices, such as video game players, DVD players, satellite receivers, and so on.
Accordingly, it would be desirable to provide a projection apparatus that is capable of emulating a remote control device such as a wireless mouse without the use of command switches. In particular, it would be desirable to provide a projection apparatus and method for locating the position of a laser spot generated by a laser pointer and using the position to control a remote device connected to the projection apparatus.